<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<img src="/images/ying.jpg" style="width: 200px;">
<h1 id="aa">demo</h1>
<button onclick="loadAjax()">ajax</button>
<form>
    <input type="file" multiple>
</form>
<script>
    function loadAjax() {
        fetch("http://localhost:8080/test").then(res => res.text()).then(str => {
            document.querySelector('#aa').innerHTML = str;
        })
    }
</script>
</body>
</html>